Tombow Mono Graph Eraser Refill is specially used for refilling the Tombow MONO graph pencil. The Tombow MONO graph pencil features one of the most popular erasers in Japan, the MONO eraser. It also features a sturdy rubber grip and a strong metal clip. Just shake the pencil up and down when you want to extend the lead. You can also extend the lead conventionally by pressing the clip down. To prevent the lead from breaking and to help with precise work, MONO graph has a 4mm long guide pipe. The high-performance MONO eraser is extendable by twisting it. Both the eraser and 0.5mm lead are refillable.